This collaborative research program is conducted jointly by Riverside Research Institute (RRI) and Cornell University Medical College (CUMC). Its long-term objective is to achieve fundamental advances in the diagnosis, treatment planning, and treatment monitoring of ocular diseases that threaten life and sight. To achieve these goals, interwoven engineering efforts (at RRI) and clinical studies (at CUMC) are investigating a variety of ultrasonic techniques that can describe tissue anatomy and microstructure. A computer-based system for acquiring and processing data and interactively displaying results has been developed and installed at CUMC to clinically evaluate these concepts. The primary technique in these studies involves calibrated spectrum analysis of radio-frequency (rf) echo signals. Spectral data have been used to establish multiparameter data bases permitting diagnosis and sub-classification of ocular tissue. In the proposed program, tissue analysis techniques will be expanded in terms of frequency coverage, volumetric averaging, types of measured features, two-dimensional spectra, and angular dependencies of echo features. Three-dimensional (3-D) scanning will be used to permit the above expansions and to provide 3-D maps of ocular anatomy and internal tissue features including tissue type, scatterer properties, and regions changed by therapy. These techniques will be used to establish data-bases to examine several ocular diseases that pose major threats to sight. In trauma and vitreous pathology studies, comprehensive anatomical descriptions together with tissue identification will be used to provide 3-D maps for surgical planning. In ocular tumor studies, data-bases will be expanded for more reliable tissue typing and subclassification, therapy planning, prognostic indices, and surgical monitoring. In glaucoma and myopia studies, morphological studies will be conducted to elucidate abnormal anatomical features and actions of therapeutic agents. Ancillary studies will provide basic knowledge concerning the interaction of tissue and ultrasound. These studies will include theoretical modelling, acoustic microscopy, and other diagnostic modalities.